Procedure for the determination of the reaction lag phase in an analyte-dependent reaction

1. A method for determining the concentration or activity of an analyte in a sample, the method comprising:

mixing a sample with at least one reagent, whereby an analyte-dependent reaction is set in motion;

measuring a signal (x) changing over time (t) as a result of the analyte-dependent reaction and storing a resultant signal-time curve;

determining a maximum increase in the signal-time curve;

determining a reaction lag phase of the signal-time curve; and

determining a concentration or activity of the analyte by means of at least one parameter of the signal-time curve, wherein the parameter occurs after the reaction lag phase in terms of time, and

wherein determining the reaction lag phase includes determining a period of time from a time of a first signal (t 0 ) up to a time t lag ,

by determining a time t max of the maximum increase in the signal-time curve; and

subsequently determining from the time t max , the time t lag , where t lag is smaller than t max and where t lag corresponds to the time at which the increase in the signal-time

curve for the first time reaches a threshold value and where the threshold value corresponds to a test-specific, predetermined fraction of the maximum increase in the signal-time curve.

2. The method of claim 1 , wherein the threshold value corresponds to a fraction of 1 to 45% of the maximum increase in the signal-time curve.

3. The method of claim 1 , wherein determining the concentration or activity of an analyte includes determining the concentration or activity of an analyte in a biological sample selected from the group consisting of whole blood, plasma, serum, urine, feces, saliva or cerebrospinal fluid.

4. The method of claim 1 , wherein the analyte-dependent reaction is an antigen-antibody reaction or an enzyme-substrate reaction.

5. The method of claim 1 , wherein measuring a signal (x) includes measuring a signal selected from the group consisting of scattered light, turbidity, fluorescence and chemiluminescence.

6. The method of claim 1 , wherein the method for determining the concentration or activity of an analyte includes determining the concentration or activity of thrombin.

7. The method of claim 6 , further comprising mixing the sample with a reagent for the activation of prothrombin to thrombin.

8. The method of claim 7 , where the sample is mixed with a reagent comprising a thrombin substrate.

9. The method of claim 8 , wherein measuring the signal (x) changing over time (t) includes measuring a signal (x) changing over time (t) as a result of the thrombin-dependent substrate cleavage and storing the resulting signal-time curve.

10. The method of claim 6 , wherein the method for determining the concentration or activity of thrombin further comprises determining the formation and inhibition of endogenous thrombin.

11. The method of claim 1 , further comprising determining a clotting time.

12. The method of claim 11 , wherein determining the clotting time includes determining a clotting time selected from the group consisting of prothrombin time, activated partial thromboplastin time, thrombin time, batroxobin time and ecarin time.

13. The method of claim 1 , wherein the at least one parameter is at least one of a maximum reaction rate, a time at which the maximum reaction rate occurs, an area under a first derivative of the signal-time curve, a time at which the signal (x) exceeds a predetermined signal, and a signal which is achieved at a predetermined time.

14. The method of claim 1 , wherein the threshold value is determined by calculating a preliminary reaction lag phase and comparing the preliminary reaction lag phase to an expected lag phase over a number of tests.

15. The method of claim 1 , wherein the maximum increase in the signal time curve is a slope of the signal time curve.